1. Field of the Invention
The present invention relates to a unified antenna of shark fin type, more specifically, a unified antenna of shark fin type which can be made relatively small and at the same time has good gain and radiation pattern conditions of antenna, thereby smoothly receiving signals of various bands, by disposing the auxiliary units contacting with the antenna units within the range of space available inside the shark fin-type antenna.
2. Background of the Invention
Generally used in a vehicle is a pole-type antenna for allowing a radio in the vehicle to receive signals.
In this regard, a conventional helical antenna is an antenna having a spiral coil structure such that resonance may be generated at antenna length(λ/4), and such a helical antenna exhibits a resonance at a specific frequency according to the length and pitch of the antenna.
However, the helical antenna is difficult to exhibit a resonance at another resonance frequency desired by users as the resonance is generated at a specific frequency of single band.
That is to say, in the case of the conventional helical antenna, primary resonance is possible, but secondary resonance is difficult to be generated at a desired frequency, and thus there is a problem that two frequencies cannot be selected.
Furthermore, there are problems that tuning is difficult, large error is generated, the return value of resonance frequency is subject to much losses, and in injecting the coil by means of a insert injection method, a state of the tuning is changed, and therefore a desired resonance frequency is not provided.
Meanwhile, recently, as various services such as mobile communication are commercialized, such new electronic products are developed, and equipped in vehicle are devices to which corresponding mobile communication technologies are applied.
In addition, in order to satisfy various desires of consumers, electronic devices for new application such as internet, TV signal reception, navigation system, DMB (Digital Multimedia Broadcasting) etc. for use in vehicle are developed.
That is to say, only function of vehicle is to simply provide the consumer with transportability, but the function has been extended recently to a concept of providing of safe, convenient and efficient transportation means.
Therefore, antenna system for vehicle for new application is required for various wireless services provided in vehicle such as internet, TV signal reception, navigation system, DMB etc. for use in vehicle, and the actual circumstance is that the antenna system gradually become more complex and is diversified due to the development of information and communication technology.
By the way, in the case of a conventional antenna system for vehicle, signal-receiving antennas for various wireless services are separately constructed for respective wireless service.
However, installing of a separate antenna for respective wireless service, as mentioned above, exhibits fundamental problems such as limitation of installation in a restricted space of vehicle and increase of installation cost etc.